Programmable charge pump

摘要

A charge pump includes a charge pump core circuit, a replica bias circuit, and a differential amplifier. The charge pump core circuit includes current source and sink circuits for charging and discharging an output node of the charge pump core circuit. The current source and current sink circuits are user programmable using bit signals to adjust a bandwidth and a phase margin of a phase-locked loop (PLL) that includes the charge pump. An impedance of the replica bias circuit varies based on the bit signals. The differential amplifier and the replica bias circuit form a feedback loop that reduces current mismatch between the current source and sink circuits.

主权项

1. A programmable charge pump, comprising:
a charge pump core circuit that receives first and second control signals, first and second bias signals, and a plurality of bit signals, and outputs a control voltage signal at an output node thereof, the charge pump core circuit comprising:
a current source circuit, connected between a supply voltage and the output node of the charge pump core circuit, that charges the output node of the charge pump core circuit based on the first control signal, wherein a current output from the current source circuit varies based on the plurality of bit signals and the first bias signal; anda current sink circuit, connected between the output node of the charge pump core circuit and ground, that discharges the output node of the charge pump core circuit based on the second control signal, wherein a current drawn by the current sink circuit from the output node of the charge pump core circuit varies based on the plurality of bit signals and the second bias signal,a source transmission gate that connects the current source to the output node of the charge pump circuit and a sink transmission gate that connects the sink circuit to the output node of the charge pump core circuit, wherein the source and sink transmission gates are controlled by the first and second control signals, respectively; a differential amplifier that receives an input signal and the first bias signal, and generates the second bias signal, wherein the input signal is at least one of the control voltage signal and a filtered version of the control voltage signal; and a replica bias circuit, connected between the differential amplifier and the charge pump core circuit, that receives the plurality of bit signals and the second bias signal and generates the first bias signal, wherein the replica bias circuit reduces a difference between the first bias signal and the control voltage signal.